Anne Arundel Medical Center expects an influx of people to move nearby as part of the federal government's military base realignment effort and other regional growth.

Central Maryland is in the midst of a health care building boom, with more than $2 billion worth of hospital expansion projects under construction or planned to begin this year in Baltimore and the surrounding counties. An additional $500 million worth of health care-related projects are in the works near local medical centers.

While other development has slowed as a result of the recession, hospitals throughout the region are adding emergency rooms, operating suites, pediatric units and other facilities. Additional life sciences buildings are opening for researchers and lab technicians who want to be near hospitals or in one of Baltimore's two bioparks.

Many of these projects were planned long before the economic downturn and are just getting off the drawing board or coming to completion. More than a few are benefiting from a decline in construction costs resulting from the lack of work elsewhere.

For the communities where they're located, these projects are welcome signs of growth in an otherwise bleak construction landscape. They also bring jobs, both within hospitals and in the form of research and other spinoff work.

"It's the great growth industry in the city," said M.J. "Jay" Brodie, president of the Baltimore Development Corp. "Not just hospitals. Research laboratories. Bioparks. Teaching facilities. Housing for people who want to be near hospitals. There's a whole network beyond just hospitals."

Behind the boom is a confluence of factors, including old buildings, a receptive bond market and a growing demand for medical services, said Pam Barclay, director of the Center for Hospital Services for the Maryland Health Care Commission.

"The thing is that it all came together," she said.

An aging population is another key factor, said Rolf Haarstad, a principal of Hord Coplan Macht, the architect for several of the projects. "We're all getting older. Our faculties are failing more. We're finding more and more things going wrong with people, because the equipment is becoming so sophisticated," he said. "The demographics are driving the work, more than anything."

At the same time, academic institutions are partnering with industry to create products for patients, and that contributes to the need for more space, said Jane Shaab, executive director of the University of Maryland-Baltimore Biopark. Companies want to be close to medical campuses and the brainpower assembled there, she said.

"It's a matter of bringing together some of the strengths we already have," she said. "This marriage of commercial activity with academic activity in the life sciences is really going to help the economy grow."

Just this month, a $160 million project at the University of Maryland Medical Center, primarily to enlarge its Shock Trauma Center, received a "certificate of need" from the Maryland Health Care Commission - the green light needed to move ahead with construction.

Administrators expect demand for trauma, emergency and critical care services to increase, and they say some areas already have reached maximum patient capacity. Shock Trauma, for example, serves more than 8,000 patients a year in a building meant to accommodate 3,500 annually when it opened in 1989. Set to begin construction in May if the state approves funding, the nine-level addition will have 10 new operating rooms.

Changing approaches to clinical care and a trend toward private rooms are also driving factors behind some projects.

Sinai, which is building a $29.5 million addition to its Herman & Walter Samuelson Children's Hospital, is expanding because it had run out of space. As one of the first hospitals in the nation to allow parents to sleep at the bedside in the pediatric intensive care unit, Sinai also wants to eliminate semi-private rooms. The latest project's design is based on "family-centered care," meaning the patient's family takes part along with the physician in the diagnosis, treatment and care of the child.

"We are going to be offering private rooms for everyone, to give not only a richer, safer environment for patients but also to give more flexibility in staffing and in providing the array of services that children need," said Warren Green, chief executive of LifeBridge Health, Sinai's corporate parent.

At Mercy, administrators note that a 1950s-era tower was designed before the invention of most bedside monitoring equipment, the passage of privacy legislation and the recognition of family and friends as contributors in the healing process. The center is replacing it with the Mary Catherine Bunting Center, a $400 million, 18-story project that will open by year's end.